What must Public Water Systems (PWS) develop according to the TCR?

Public Water Systems (PWS) are required to develop a monitoring plan that includes regular sampling to ensure that the water meets safety standards. According to the Total Coliform Rule (TCR), the correct approach is to implement a plan that mandates monthly sampling at each monitoring point. This frequency of testing is crucial because it helps verify the absence of coliform bacteria, which can indicate potential contamination and health risks for consumers. Monthly sampling allows early detection of issues and provides a comprehensive assessment of water quality, supporting public health protection.

The other choices involve aspects of water treatment and monitoring but do not align with the specific requirements set forth by the TCR regarding the frequency and type of monitoring needed for public water systems. For instance, quarterly sampling may not provide adequate oversight in identifying potential coliform outbreaks promptly. Similarly, while treatment technique plans are necessary for compliance with other regulations concerning chemical contaminants, they do not pertain directly to the coliform monitoring mandated by the TCR. Therefore, the emphasis on regular monthly monitoring establishes a critical framework for ensuring safe drinking water through consistent oversight.